Rotary valve structure for four-stroke engine

ABSTRACT

A rotary valve structure is provided for a four-stroke engine having a cylinder in which a piston is brought by a crankshaft to move in reciprocating motion and a combustion chamber is provided to communicate with separated gas-in and gas-out passages. The rotary valve structure includes an intake and an exhaust rotary rod rotatably located at a gas inlet of the gas-in passage and a gas outlet of the gas-out passage, respectively. The intake and the exhaust rotary rods are rotated by a transmission mechanism driven by the crankshaft, such that an intake and an exhaust hole radially extended through the intake and the exhaust rotary rod, respectively, are turned either to communicate the gas-in and the gas-out passages with the combustion chamber or to close the gas-in and said gas-out passages at the gas inlet and the gas outlet.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a rotary valve structure for four-stroke engine, and more particularly to valves for four-stroke engine that are driven by a rotating crankshaft of the engine to move in rotary motion and replace the conventional valves moving in linear reciprocating motion.

[0002] When a piston of the conventional four-stoke engine is moved in a cylinder in reciprocating motion, mixed gas is admitted into and exhausted from the cylinder via valves. Most of the currently available valves for the four-stroke engine move in linear reciprocating motion, and there are a lot of problems with such linearly reciprocatingly moved valves.

[0003] FIGS. 1 to 4 shows basic structure and movements of a cylinder 10 of the conventional four-stroke engine. The cylinder 10 internally includes a piston 13 that is connected to a crankshaft 11 via a connecting rod 12 so as to reciprocatingly move in the cylinder 10 when being driven by the crankshaft 11. The cylinder 10 is provided at an end with an intake valve 14 and an exhaust valve 15, and a spark plug 16 located between the two valves.

[0004] Please refer to FIG. 1. When the intake valve 14 is linearly moved inward to an open position, mixed gas is admitted into the cylinder 10 in a direction indicated by the arrow. When the crankshaft 11 rotates, the piston 13 is driven to move upward and compress the mixed gas in the cylinder 10, as shown in FIG. 2. The compressed mixed gas is ignited by the spark plug 16, explodes, and burns in the cylinder 10 to produce pressure that is acted on a top of the piston 13, as shown in FIG. 3. The piston 13 is therefore pushed downward. At this point, the exhaust valve 15 is opened, and the piston 13 is moved upward again due to inertia of the rotating crankshaft 11, so that exhaust is discharged from the cylinder 10 via the opened exhaust valve 15.

[0005] In the above-described movements of the four-stroke engine, both the intake and the exhaust valves 14, 15 move in linear reciprocating motion and the following problems are found in these linearly moved valves:

[0006] 1. A high-speed inertia of the valves moving in linear reciprocating motion tends to cause inaccurate movements of the valves. Additional return means, such as springs (not shown), must be provided for the valves to return to their exact original positions, extra force and energy are therefore consumed in the operation of the cylinder.

[0007] 2. Belts (or chains) for driving the valves to move are possibly broken during the driving to cause interference and collision of the valves with the piston.

[0008] 3. The intake valve 14 usually has a valve shaft having a diameter smaller than that of a valve plate connected to an end of the valve shaft. When the intake valve 14 is moved inward to the open position as shown in FIG. 1, the gas tends to flow into the cylinder 10 along the thin valve shaft to produce only a reduced eddy effect in the cylinder 10.

SUMMARY OF THE INVENTION

[0009] It is therefore a primary object of the present invention to provide a rotary valve structure for four-stroke engine to effectively eliminate the problems existing in the four-stroke engine with conventional linearly reciprocatingly moved valves, and to advantageously increase the horsepower of the engine.

[0010] To achieve the above and other objects, the rotary valve structure of the present invention mainly includes an intake and an exhaust rotary valve containing an intake and an exhaust hole, respectively. The intake and the exhaust rotary valves are driven by the crankshaft of the engine via a transmission mechanism to move in rotary motion in controlling gas introduction, gas compression, and gas exhaust of the engine.

[0011] In a preferred embodiment of the present invention, the intake rotary valve has a diameter larger than that of the exhaust rotary valve, and the intake hole is larger than the exhaust hole.

[0012] In the present invention, the transmission mechanism includes an extending shaft provided along an end of the driving crankshaft of the engine, a belt pulley, a driving belt having an end supported on the extending shaft and anther end on the belt pulley for the belt pulley to rotate along with the crankshaft, and a driving screw fixedly connected to a center at one side of the belt pulley facing toward the cylinder. The intake and the exhaust rotary valves are located at two sides of the driving screw to mesh their externally threaded portions with the driving screw, and thereby brought to rotate by the driving screw.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

[0014] FIGS. 1 to 4 shows movements of a conventional four-stroke engine;

[0015]FIG. 5 is a perspective view of a rotary valve structure for four-stroke engine according to a preferred embodiment of the present invention;

[0016]FIG. 6 is a sectioned side view showing the present invention is in a position for admitting gas into a cylinder of the engine;

[0017]FIG. 7 is a sectioned side view showing the present invention is in a position to close the cylinder;

[0018]FIG. 8 is a sectioned side view showing the present invention is in a position for exhausting gas from the cylinder; and

[0019]FIG. 9 shows another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Please refer to FIG. 5 that is a perspective view of a rotary valve structure for a four-stroke engine according to a preferred embodiment of the present invention. To better show an overall structure of the present invention, the main body of a cylinder 60 with which the present invention is associated is omitted from the drawing. The four-stroke engine includes a piston 20 connected to a crankshaft 22 via a connecting rod 21, so that the piston 20 and the connecting rod 21 are brought by the crankshaft 22 to move in reciprocating motion in the cylinder.

[0021] An extending shaft 23 is provided along an end of the crankshaft 22 (it is the left end in the illustrated drawing) for supporting an end of a driving belt 24, an opposite end of which is mounted around a belt pulley 25 to drive the same to rotate along with the crankshaft 22. A driving screw 26 projects from a center at one side of the belt pulley 25 that faces toward the cylinder to synchronously rotate with the belt pulley 25. An intake and an exhaust rotary rod 30 and 40, respectively, are located at two sides of the driving screw 26. Both the intake and the exhaust rotary rods 30, 40 are provided at an end adjacent to the belt pulley 25 with an externally threaded portion 31, 41 for meshing with the driving screw 26, such that the intake and the exhaust rotary rods 30, 40 rotate along with the driving screw 26 at the same time. In the illustrated preferred embodiment, the intake rotary rod 30 has a main body having a diameter larger than that of a main body of the exhaust rotary rod 40. Moreover, the intake and the exhaust rotary rods 30, 40 are provided at the main bodied with radially extended intake hole 32 and exhaust hole 42, respectively. The intake hole 32 is larger than the exhaust hole 42.

[0022] Although not shown in the drawing, it is understood a locating cover having preformed openings may be provided at a top of the cylinder for laterally holding the intake and the exhaust rotary rods 30, 40 in place and vertically holding a spark plug 50 of the engine in place. The spark plug 50 is used to ignite mixed gas admitted into the cylinder via the intake rotary rod 30.

[0023] Please now refer to FIG. 6 that is a sectioned side view showing the intake and the exhaust rotary rods 30, 40 are in positions for admitting mixed gas into the cylinder 60. As shown, the intake and the exhaust rotary rods 30, 40 are located at a gas inlet of a gas-in passage 62 and a gas outlet of a gas-out passage 63, respectively, of the cylinder 60. When the intake rotary rod 30 is rotated to align the intake hole 32 with the gas-in passage 62 to communicate the latter with a combustion chamber 61 in the cylinder 60 at the gas inlet, mixed gas can be introduced into the cylinder 60 in a direction indicated by the arrows. Thereafter, the piston 20 is caused to move upward and compress the mixed gas having been introduced into the combustion chamber 61, as shown in FIG. 7, and the spark plug 50 is used to ignite the mixed gas. At this point, the intake and the exhaust rotary rods 30, 40 are rotated for the intake and the exhaust holes 32, 42 to turn away from the gas-in and the gas-out passages 62, 63, respectively, so that the gas inlet and the gas outlet are closed. When the piston 20 is linearly moved downward in its reciprocating motion, the exhaust rotary rod 40 is turned to align the exhaust hole 42 with gas-out passage 63 to communicate the same with the combustion chamber 61, as shown in FIG. 8, so that exhaust could be discharged from the cylinder 60 via the exhaust rotary rod 40 and complete a four-stroke cycle of the engine.

[0024]FIG. 9 shows another embodiment of the present invention. In this embodiment, the intake rotary rod is replaced with a hollow intake rotary tube 30 defining a bore 33 for movably receiving a movable stick 80 therein, and a top cover 70 is provided for holding the intake rotary tube 30, the exhaust rotary rod 40, and the spark plug 50 in place. This embodiment is particularly suitable for use with a direct-injection engine. With the movable stick 80 disposed in the rotary intake tube 30, gas flow passing the intake rotary tube 30 can be controlled without using a conventional throttle valve. This embodiment enables the intake hole 32 to reduce when the engine is at a low rotational speed, so as to obtain increased gas flow rate and accordingly increased torsion.

[0025] With the above arrangements, the intake and the exhaust holes 32, 42 are moved into positions for directly communicating with the combustion chamber 61 through rotary motion when the cylinder 60 works. This enables the rotary valve structure of the present invention to admit and exhaust gas in a more advantageous and smooth manner, as compared with the conventional linearly moved valves. The present invention also has the following advantages:

[0026] 1. Since the intake and the exhaust rotary rods 30, 40 and the crankshaft 22 all are rotary gears, the problem of inaccurate movement of the conventional valves due to high-speed inertia can be eliminated.

[0027] 2. There is no need to use any return spring to pull the valves to their original positions, the present invention is therefore simpler in structure and can operate with reduced energy.

[0028] 3. Since the intake and the exhaust rotary rods 30, 40 are provided at an end of the cylinder 60 to control the introduction and exhaust of gas into and from the cylinder 60 through rotational movements of the rods 30, 40, breaking of the driving belt 24 would not cause interference and collision of the piston 20 with the valves 30, 40.

[0029] 4. The intake hole 32 of the intake rotary rod 30 can be turned to align with the combustion chamber 61 when the cylinder 60 works, enhanced eddy effect and increased eddy velocity of fuel gas could therefore be obtained.

[0030] Ways for an internal combustion engine to increase its horsepower generally include taking in more carbureted mixture, having an airtight combustion chamber, reducing the temperature of the introduced gas, and increasing the eddy velocity of the fuel gas. In the present invention, since the intake and the exhaust holes may be designed to different sizes and allow direct introduction of fuel gas and discharge of exhaust via straight paths provided by the valves 30, 40 between the combustion chamber 61 and the gas-in and the gas-out passages 62, 63, respectively, more carbureted mixture can be advantageously taken into the cylinder to increase the eddy velocity of the fuel gas. Moreover, mixed gas can be directly injected into the combustion chamber via the intake hole 32 that is provided with an increased diameter, so that increased eddy velocity of the fuel gas and increased horsepower of the internal combustion engine can be obtained.

[0031] The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention as defined by the appended claims. 

What is claimed is:
 1. A rotary valve structure for four-stroke engine, said engine including a cylinder in which a piston is brought by a crankshaft to move in reciprocating motion, and said cylinder being provided at one end with separated gas-in and gas-out passages that communicate with a combustion chamber in said cylinder, comprising an intake rotary rod and an exhaust rotary rod rotatably located at a gas inlet of said gas-in passage and a gas outlet of said gas-out passage, respectively; said intake and said exhaust rotary rods being connected to a transmission mechanism that is connected to and driven to rotate by said crankshaft, such that an intake hole and an exhaust hole provided on said intake rotary rod and said exhaust rotary rod, respectively, to radially extend therethrough are oriented either to communicate said gas-in and said gas-out passages with said combustion chamber or to close said gas-in and said gas-out passages at said gas inlet and said gas outlet.
 2. The rotary valve structure for four-stroke engine as claimed in claim 1, wherein said intake rotary rod has a diameter larger than that of said exhaust rotary rod, and said radially extended intake hole of said intake rotary rod is larger than said radially extended exhaust hole of said exhaust rotary rod.
 3. The rotary valve structure for four-stroke engine as claimed in claim 1, wherein said transmission mechanism includes an extending shaft provided along an end of said crankshaft, a driving belt, and a belt pulley; said driving belt being supported at an end on said extending shaft and at another end on said belt pulley, so that said belt pulley rotates along with said crankshaft synchronously; and said intake rotary rod and said exhaust rotary rod being connected to one side of said belt pulley and brought to rotate by said belt pulley.
 4. The rotary valve structure for four-stroke engine as claimed in claim 3, wherein said belt pulley includes a driving screw fixedly mounted at a center of said side of said belt pulley having said intake and said exhaust rotary rods connected thereto, and said intake and said exhaust rotary rods being located at two sides of said driving screw, and being externally provided at predetermined positions with threads for meshing with said driving screw.
 5. The rotary valve structure for four-stroke engine as claimed in claim 1, wherein said intake rotary rod defines an inner bore for movably receiving a movable stick therein to control an intake flow at said intake hole. 